Chill mold



Dec. 7, 1937.

E. MAHLE CHILL MOLD 7 Filed Aug. 18, 1936 2 Sheets-Sheet 1 A L: 5 ZNVaN POP Dec. 7, 1937.

E. MAHLE CHILL MOLD Filed Aug. 18, 1936 2 Sheets-Sheet 2 V 6' l liik ak- Patented Dec. 7, 1937 UNITED STATES CHILL MOLD Ernst Mahle, Stuttgart, Germany Application August 18, 1936, Serial No. 96,663 In Germany October 19, 1935 ing engine pistons which consist of a plurality of light metal alloys which are joined together forming an intermediate alloy in-the boundary zone, or zones, in a state between fusion and viscidity.

Casting arrangements for manufacturing composite castings are known in which the hollow spaces of .the mold are separated by means of inserted partitions. After one of the spaces has been'filled and the surface of this part of the ingot has set, the partition is removed and the metal for the second part of the ingot is poured in, which then becomes welded to the solidified surface of the first part of the ingot.

In another known method of casting compound ingots and castings using a removable is forced under pressure and in the absence of air into the mixing zone of the fused metals.

The mold according to the present inven-' tion is distinguished from these known casting arrangements for making compound ingots or -castings by the fact that after the running in of the first alloy a part of the inner surface of the wall of the mold can be changed in shape by-b eing displaced; In this way it is made posis provided in the bottom of the mold in order' sible to provide at any desired part of a piston,

'a part consisting of a given light metal alloy, while the remaining part of the piston body consists of another definite light metal alloy. This method of compound casting is chosen in order that the different stresses atthe individual parts of the piston may be taken into consideration in choosing the different alloys.

, constructional examples of the invention are illustrated diagrammatically in the accompanying drawings.

Fig. 1 shows a casting arrangement in longitudinal section, in which a slidable insertion to obtain in the middle of the end of the piston a corresponding alloy part. The figure shows the casting arrangement before the introduction of the fused metal.

Fig. 2 shows the same casting arrangement casting insertions that the second alloy part is introduced at the edge of the end of the piston in the form of an annulus.

Fig. 4 shows the casting arrangement according to Fig. 3 after the casting is finished.

In the constructional example illustrated of the casting arrangement according to the invention I is the bottom of the mold, while the lateral halves of the mold are indicated by 2. The cores 3. for the gudgeon pin. bearing extend up to the three-part piston core, the lateral parts 4 of which, shown in elevation, enclose the middle part 5.

, In the bottom I of the mold the insertion 6 is .arranged slidably and may be mounted in a second insertion I, in which case however, both insertions are movable independently.

The casting operation with the casting arrangement with single and double insertions will be described below.

In the constructional example according to Figs. 1 and 2 before the beginning of the casting operation, the-insertion 6 in the bottom .I of the mold is drawn so far down that the free space formed in the upper part of the bottom of the mold is'filled with the first fused metal. While this is still in a state lying between fusion and viscidity the insertion 6 is pushed upwards, and at the same time the second fused metal is poured into the mold and occupies the remaining space 9. As shown in Fig. 2, when' the casting operation is ended there is obtained a compound piston casting consisting of two-light metal alloys, one of the alloys filling an approximately cylindrical space in the centre of the top of the piston.

In the constructional example according to Figs. 3 and 4 the insertions 6 and I are arranged before the casting operationin such a manner that both parts extend into the space with end surfaces Ill in contact, so that an annular space ll round the edge of the top of the piston is formed-for the first alloy.- After both insertions have been withdrawn simultaneouslythe second fused metal is added and a piston construction as shown in Fig. 4 is obtained. It is also possible to use a different arrangement of the relatively movable insertions, for example in' order to cast, in addition to the annular part at the edge of the top of the piston, an alloy in the zone of the middle of the top of the piston, which may have additional or .different properties from the alloy used for the re- =maining part of the piston body l2.

What I claim is:

l. A chill mold for casting pistons which con- 10 a side wall and a bottom wall, a plurality of movable members, one of said members bein arranged within the'other, said members being mounted within the bottom wall of said mold and movable relative to one another, each of said members being of a shape which is similar to that of the space to be occupied by one of the alloys in the piston to be cast, and the inner boundary of one movable part forming the thrust surface of another part.

ERNST MAHLE. 

